In the field of polymerization of alpha-monoolefins, such as propylene, or ethylene, to produce useful polymers, a continuing objective is an increase in productivity relative to the amount of catalyst employed. Productivity is highly important in order to keep to a minimum the amount of residual catalytic materials to be removed from the resulting polymer which is almost always a necessity, and generally is a troublesome or relatively expensive procedure to carry out.
In another aspect, normally the desired polymer is a solid polymer, and minimization of the formation of "solubles", i.e. amorphous or atactic polymer, is a much to be desired objective. Most amorphous polymer is considered an undesirable byproduct, which either degrades the character of the total product, or else must be removed by treating with such as hexane, to recover the more valuable solid polymer for exploitation.
Thus, it is desired to provide polymerization processes, and catalysts, effective in improving the productivity of the polymerization of alpha-monoolefins, and also to minimize the formation of solubles.